Phase transformations in two-layered In₂Se₃-Cu film system
In the article Cu-In-Se thin films obtained by dosed deposition of Cu onto indium selenide starting layer with the further annealing of the two-layered composition in Se atmosphere were investigated by transmission electron microscopy (TEM) and by energy-dispersive X-ray spectroscopy (EDS). The...
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Національний технічний університет КПІ України
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irk-123456789-1110802018-03-21T13:15:57Z Phase transformations in two-layered In₂Se₃-Cu film system Grigorov, S.N. Kosevich, V.M. Kosmachev, S.М. Taran, А.V. Физика радиационных и ионно-плазменных технологий In the article Cu-In-Se thin films obtained by dosed deposition of Cu onto indium selenide starting layer with the further annealing of the two-layered composition in Se atmosphere were investigated by transmission electron microscopy (TEM) and by energy-dispersive X-ray spectroscopy (EDS). The samples with various Cu content, Cu/In<1 and Cu/In>1, were prepared. It was revealed that all films after selenization had a modulated structure, which was formed due to Cu diffusion into the indium selenide film. Such modulated structures have been formed by both equilibrium phases of the Cu₂Se-In₂Se₃ pseudo-binary section of the Cu-In-Se ternary system and by metastable ones. Проведені електронно-мікроскопічне та рентгеноспектральне дослідження плівок Cu-In-Se, отриманих шляхом дозованого осадження міді на шар селеніду індію та відпалу двошарової композиції в атмосфері селену. Були виготовлені зразки із різною концентрацією міді (Cu/In<1 і Cu/In>1). Установлено, що всі плівки після селенізації мають модульовану структуру, що формується в результаті дифузії міді в плівку селеніду індію. Спостерігалися модульовані структури, утворені як рівноважними фазами, що належать псевдобінарному перетину Cu₂Se-In₂Se₃ трикомпонентної системи Cu-In-Se, так і метастабільними фазами. Проведены электронно-микроскопическое и рентгеноспектральное исследования плёнок Cu-In-Se, полученных путём дозированного осаждения меди на слой селенида индия и отжига двухслойной композиции в атмосфере селена. Были приготовлены образцы с различной концентрацией меди (Cu/In<1 и Cu/In>1). Установлено, что все пленки после селенизации имеют модулированную структуру, которая формируется в результате диффузии меди в пленку селенида индия. Наблюдались модулированные структуры, образованные как равновесными фазами, принадлежащими псевдоби- нарному сечению Cu₂Se-In₂Se₃ трехкомпонентной системы Cu-In-Se, так и метастабильными фазами. 2008 Article Phase transformations in two-layered In₂Se₃-Cu film system / S.N. Grigorov, V.M. Kosevich, S.М. Kosmachev, А.V. Taran // Вопросы атомной науки и техники. — 2008. — № 2. — С. 145-148. — Бібліогр.: 12 назв. — англ. 1562-6016 http://dspace.nbuv.gov.ua/handle/123456789/111080 539.218.3 en Вопросы атомной науки и техники Національний технічний університет КПІ України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
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English |
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Физика радиационных и ионно-плазменных технологий Физика радиационных и ионно-плазменных технологий |
| spellingShingle |
Физика радиационных и ионно-плазменных технологий Физика радиационных и ионно-плазменных технологий Grigorov, S.N. Kosevich, V.M. Kosmachev, S.М. Taran, А.V. Phase transformations in two-layered In₂Se₃-Cu film system Вопросы атомной науки и техники |
| description |
In the article Cu-In-Se thin films obtained by dosed deposition of Cu onto indium selenide starting layer with the
further annealing of the two-layered composition in Se atmosphere were investigated by transmission electron microscopy
(TEM) and by energy-dispersive X-ray spectroscopy (EDS). The samples with various Cu content, Cu/In<1
and Cu/In>1, were prepared. It was revealed that all films after selenization had a modulated structure, which was
formed due to Cu diffusion into the indium selenide film. Such modulated structures have been formed by both equilibrium
phases of the Cu₂Se-In₂Se₃ pseudo-binary section of the Cu-In-Se ternary system and by metastable ones. |
| format |
Article |
| author |
Grigorov, S.N. Kosevich, V.M. Kosmachev, S.М. Taran, А.V. |
| author_facet |
Grigorov, S.N. Kosevich, V.M. Kosmachev, S.М. Taran, А.V. |
| author_sort |
Grigorov, S.N. |
| title |
Phase transformations in two-layered In₂Se₃-Cu film system |
| title_short |
Phase transformations in two-layered In₂Se₃-Cu film system |
| title_full |
Phase transformations in two-layered In₂Se₃-Cu film system |
| title_fullStr |
Phase transformations in two-layered In₂Se₃-Cu film system |
| title_full_unstemmed |
Phase transformations in two-layered In₂Se₃-Cu film system |
| title_sort |
phase transformations in two-layered in₂se₃-cu film system |
| publisher |
Національний технічний університет КПІ України |
| publishDate |
2008 |
| topic_facet |
Физика радиационных и ионно-плазменных технологий |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/111080 |
| citation_txt |
Phase transformations in two-layered In₂Se₃-Cu film system / S.N. Grigorov, V.M. Kosevich, S.М. Kosmachev, А.V. Taran // Вопросы атомной науки и техники. — 2008. — № 2. — С. 145-148. — Бібліогр.: 12 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT grigorovsn phasetransformationsintwolayeredin2se3cufilmsystem AT kosevichvm phasetransformationsintwolayeredin2se3cufilmsystem AT kosmachevsm phasetransformationsintwolayeredin2se3cufilmsystem AT taranav phasetransformationsintwolayeredin2se3cufilmsystem |
| first_indexed |
2025-07-08T01:35:26Z |
| last_indexed |
2025-07-08T01:35:26Z |
| _version_ |
1837040693313273856 |
| fulltext |
UDC 539.218.3
PHASE TRANSFORMATIONS IN TWO-LAYERED
In2Se3-Cu FILM SYSTEM
S.N. Grigorov, V.M. Kosevich, S.М. Кosmachev, А.V. Тaran
National Technical University KPI, Kharkov, Ukraine
In the article Cu-In-Se thin films obtained by dosed deposition of Cu onto indium selenide starting layer with the
further annealing of the two-layered composition in Se atmosphere were investigated by transmission electron mi-
croscopy (TEM) and by energy-dispersive X-ray spectroscopy (EDS). The samples with various Cu content, Cu/In<1
and Cu/In>1, were prepared. It was revealed that all films after selenization had a modulated structure, which was
formed due to Cu diffusion into the indium selenide film. Such modulated structures have been formed by both equilib-
rium phases of the Cu2Se-In2Se3 pseudo-binary section of the Cu-In-Se ternary system and by metastable ones.
1. INTRODUCTION
At present, α-CuInSe2 (α-CIS) semiconductor com-
pound with a chalkopyrite-type structure and its solid
solutions are the most promising materials for realizing
a new generation of thin film solar cells [1-4]. One of
the advantageous methods to produce CuInSe2 base lay-
ers is sequential vacuum deposition of indium selenide
and copper with the following annealing in selenium at-
mosphere (selenization) of the two-layered composition
[5-9].
From the literature [10-11] it is reported that in at-
tempting to synthesize a chalkopyrite phase, a number
of additional phases were identified, namely: δ-CuInSe2,
CuIn3Se5 (β-phase CIS with a chalkopyrite structure
with ordered vacancies in Cu sub-lattice), CuIn5Se8 (γ-
CIS), Cu2In4Se7, Cu3In5Se9, Cu5InSe4, Cu7In19Se32,
Cu8In18Se33. The main difficulty that arises during phase
identification is the fact that the electron-diffraction pat-
terns taken from these films contain only several intense
lines and a great number of very weak ones. In so doing,
the crystallographic parameters of different phases are
so close to each other and to the parameters of the base
Cu2Se and In2Se3 phases that these intense lines cannot
be identified by TEM.
In the article, Cu-In-Se thin films obtained by dosed
deposition of Cu onto indium selenide starting layer
with the further annealing of the two-layered composi-
tion in Se atmosphere were investigated by transmission
electron microscopy (TEM) and by energy-dispersive
X-ray spectroscopy (EDS). The samples with various
Cu content, Cu/In<1 and Cu/In>1 were prepared. All
films were annealed in a Se atmosphere at 550 °C. The
elemental and phase compositions as well as the struc-
ture of the obtained films were determined. The CIS
growth mechanism in the two-layered film system was
examined.
2. METHOD AND PREPARATION
Copper (purity 99,999%) was deposited in a 10-3 Pa
vacuum at 200 °C onto In(Se) layer, which was previ-
ously formed with a sequence: In2Se3 (Тsub=250 °C)+Se
(Тsub=350 °C)+In2Se3 (Тsub=500 °C) + Se (Тsub=550 °C).
Next, the two-layered In2Se3-Cu composition was an-
nealed in a Se atmosphere at 550 °C. The elemental
composition of the samples with different Cu content
was analyzed by EDS, while the structure was investi-
gated by TEM.
3. RESULTS AND DISCUSSION
The samples of three types were prepared. Accord-
ing to EDS data, the samples of the first type were Cu-
poor. Cu/In ratio was 0,64 as compared to a stoichio-
metric CIS. On the β-In2Se3-Cu2Se quasi-binary section
of the Cu-In-Se equilibrium phase diagram, this chemi-
cal composition corresponds to the region of the β-CIS
phase. The samples of the second type had the Cu/In ra-
tio equal to 1,12, and the samples of the third type had a
composition with Cu/In = 1,25. The samples of the sec-
ond and third types were attributed to the two-phase (α-
CuInSe2 + Cu2Se) region of the Cu-In-Se equilibrium
phase diagram. All samples had an excess of Se as com-
pared to stoichiometric CuInSe2.
Fig. 1,a-c represents typical structure and microd-
iffraction patterns of the first type films. A complex
contrast in the form of dark and bright triangles was re-
vealed in Fig. 1,a. Such a contrast may be formed either
by stacking faults lying parallel to the film surface or by
thin lamellas of secondary phases with a lattice that cor-
relates coherently with that of a base matrix.
Microdiffraction pattern taken from this area ex-
hibits the reflections with hexagonal symmetry corre-
sponding to the (001) plane of the β-In2Se3 or CuIn5Se8
(γ-CIS) phases, which have hexagonal lattices with
close parameters. But the most intense reflections (see
Fig. 1,a), may be originated from both (300) β-In2Se3,
(110)γ-CIS, and (220) α- or β-CIS phases. Weak reflec-
tions in a position of ½ (200) corresponding to α-CIS,
which closely fitted to these of (100)-type β-CIS were
also revealed. Basing on this data, one can conclude that
in a plane normal to the electron beam, the platelets of
at least twophases (γ-CIS and β-CIS) are matched in
such a manner that their crystallographic relationships
are as follows: (001)γ-CIS || (112) β-CIS. In these phas-
es, the planes are occupied only by Se atoms and have
an identical structure. The distance between Se atoms in
the (001) plane of hexagonal γ-CIS is 0,404 nm [4],
whereas along the (112) plane of the β-CIS it corre-
sponds to 0,407 nm [4]. A mismatch between these two
_________________________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2008. № 2.
Серия: Физика радиационных повреждений и радиационное материаловедение (92), с. 145-148.
145
lattices is 0,7% and it can be compensated by elastic de-
formations of the lattices and by the formation of a tri-
angular network of misfit dislocations. There is also a
good correlation between crystalline lattices of β-In2Se3
and γ-phase CIS: 3аγ-phase ≅ 3 аβ-In2Se3. Along (001)
plane they form a common boundary with a “discrepan-
cy” of 1,5%. This mismatch is partly compensated by
elastic deformations of the lattices or by triangular net-
work of grain-boundary dislocations. With such a corre-
lation the microdiffraction patterns of these two phases
are almost identical. Strong diffuse coils, observed in
Fig. 1,a, may originate from the γ-CIS phase with a lat-
tice containing Cu-excess atoms – zones of β-CIS phase
(like Guiner-Preston zones). Assuming the above men-
tioned, one can speculate that in a direction normal to
the film surface and on the base of β-In2Se3 grains (001
plane || to the film surface), take place the formation of
three-layered structure, containing β-In2Se3 - γ-CIS - β-
CIS phases, which are in coherent position.
In a grain marked A (see Fig. 1), one can observe a very
thin lamellas lying parallel to the electron beam. At mi-
crodiffraction pattern, such a grain revealed strong re-
flection of (112) type, which was attributed to both β-
and α-CIS phases. A long bar extends from such a re-
flection and this also points to the existence of thin
lamellas in this grain. In addition, there are some lamel-
las along (112) plane inclined to the electron beam. On
these lamellas we revealed a striped contrast like from
inclined staking faults. Obviously, in this case we deal
with thin lamellas of the α-phase incorporated into β-
matrix.
In Fig. 1,b, we observed a line of closely pitched re-
flections associated with γ-CIS with trigonal lattice [4].
Fig. 1,c shows electron-diffraction image and microd-
iffraction pattern taken from the film area, where in the
direction of an electron beam the two layers of the γ-
phase with trigonal and hexagonal lattices are formed.
The microstructure and microdiffraction patterns of
films of the second type with Cu/In = 1,12 are shown in
Fig. 2. Such a structure is mainly characterized by a
great number of thin twinned lamellas. Among the phas-
es that are formed in a considered system, the twins can
originate only in phases with a chalkopyrite structure
i.e. α- or β-CIS. In a chalkopyrite structure the twinning
take place along (112)-type planes which form tetrahe-
dron. Microdiffraction pattern (see Fig. 2) has verified
the fact that in lamella crystallite with the structure of β-
phase with (112) plane parallel to the film surface take
place the formation of thin twinned lamellas along three
another tetrahedron planes. It is in this case that we had
observed cross-like bars near the (112)-type reflections.
The intensification at the ends of such cross-like bars
has also drawn our attention. This phenomenon may
take place, when the Evald’s sphere is crossed by
strained sites of (101) and (103)-types of the invert lat-
_________________________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2008. № 2.
Серия: Физика радиационных повреждений и радиационное материаловедение (92), с. 145-148.
(300) β-In
2
Se
3,
(110) γ-
CIS,
(220) α-CIS,βCIS
(110) β-CIS
a
0,2 mµ
γ- CIS(hex.)
γ- CIS(trig.)
c
0,2 mµ
(112)β-CIS
(001)…(0010) γ-CIS
b
A
0,25 mµ
Fig. 1. TEM images and microdiffraction patterns from the film of the
first type, Cu/In = 0,64
146
tice of chalkopyrite structure with microtwins along all
tetrahedron planes. As the films of the second type had
a great amount of β-phase, which is In- rich, there re-
mains an excess of Cu. Therefore, the excess of Cu in-
teracts with Se and the film should contain Cu2Se phas-
es. However, in our investigations we could not find any
traces of Cu-rich selenides.
Fig. 2. TEM image and microdiffraction pattern from
the film of the second type, Cu/In = 1,12
The microstructure of the films of the third type
(Cu/In ratio 1,25) had almost the same features as com-
pared to the structure of the second type films. Here, we
have also revealed a number of packets with parallel mi-
crotwins of α- and β-CIS. But, in this case, such thin
lamellas of the β-CIS were incorporated into grain ma-
trix of α-phase. At microdiffraction pattern in Fig. 3,a,
the hexagonal reflection network corresponds to a large
crystallite of the α-phase lying in the (112) CuInSe2
plane parallel to the film surface, whereas (110)-type re-
flections of the β-phase with bars were very weak.
The reflections in a position of 1/3(424) and
2/3(424) of CuInSe2 phase were also observed in the
film. They can originate from the twin boundaries.
There was revealed a number of large grains with mi-
crotwins attributed to α-CIS only (see Fig. 3,b). From
these twinned crystallites we revealed the existence of
(220)-type reflections but without the indication of
(110) ones. Evidently, the transformation from the
twinned lamella crystallites of the β-phase to these of
the α-phase took place via formation of modulated
structures, which consist of alternating twinned lamellas
of α- and β-phases. As the films of the third type were
Cu-rich, so they should contain Cu2Se, however, at mi-
crodiffraction patterns cooper selenide was not found.
But there was revealed a great number of similar lamel-
la structures with phases, which we couldn’t attribute to
any of known In-Se, Cu-Se or Cu-In-Se compounds.
This situation can be explained basing on the ideas de-
scribed in [12]. All observed phases in the samples that
correspond to β-In2Se3-Cu2Se pseudo- binary section of
the Cu-In-Se phase diagram have common crystallo-
graphic features. They are formed by alternating closed-
packing Se layers and of these containing only cation of
metals.
The crystalline lattices of these two phases may cor-
relate by a common anion plane
In so doing, along with equilibrium phases the
metastable homogeneous modifications can also be
present in the film. On microdiffraction patterns these
_________________________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2008. № 2.
Серия: Физика радиационных повреждений и радиационное материаловедение (92), с. 145-148.
(110)β-CIS
(101)
α-CIS
(103)
0,2 mµ
(220) α-CIS
(110) β-CIS
1/3 (424)
(424) α-CIS
2/3(424)
0,1 mµ
0,1 mµb
α-CIS
220
116
а
Fig. 3. TEM images and microdiffraction patterns from the film of the third
type, Cu/In = 1,25
147
modifications reveal reflections which are different
from those of equilibrium phases. Besides that, some
additional reflections were revealed due to diffraction
on the modulated structures.
In all considered cases of phase formations in the
two-layered In2Se3/Cu film composition we have deter-
mined two situations. In the film area in which indium
selenide film contains grains with (001) plane parallel to
the film surface, in initial two-layer composition take
place the formation of multi-layered on thickness grains.
The copper content is increased layer by layer from
some minimal value dependent on Cu/In ratio in this
system to a maximal, which is also determined by this
ratio.
Thus, in films with Сu/In = 0,64 we observed the
transition from In2Se3 to β-phase CuIn3Se5, whereas in
films with Сu/In = 1,25 take place the transition from β-
phase CuIn3Se5 to CuInSe2 or possibly to Cu2Se. In
some areas of the film in which indium selenide film is
lying normal or inclined to the film surface, Cu diffuses
through the bulk of indium selenide layer. In this case,
alternating plates of two phases, lying normal or in-
clined to the film surface split indium selenide grains.
So, the modulated structures were formed due to trans-
formation of indium selenide cation sub-lattice. In a set
of crystallographic modifications, which form modulat-
ed structure can exist both stable and metastable modifi-
cations.
CONCLUSIONS
It was revealed that all films after selenization had
modulated structure, which was formed due to Cu diffu-
sion into the In(Se) film. The modulated structures were
formed by both equilibrium phases of the In2Se3-Cu2Se
pseudo-binary section of the Cu-In-Se ternary system
and by metastable phases. In Cu-poor films, (Cu/In<1)
such modulated structures were formed basing on the
In2Se3, CuIn5Se8 and CuIn3Se5 phases. In Cu-rich films,
the formation of modulated structures is based on
CuIn3Se5 and α-CuInSe2 phases. The correlation of
phases in modulated structures is accomplished either
by coherent phase boundaries, which contain misfit
dislocations or by means of twinned boundaries. The
most perfect structure had the films with Cu/In = 1,2.
They contain large grains (~0,5 µm) of α-CIS with a
great number of thin twinned lamellas of α- and β-CIS.
REFERENCES
1. А. Rockett, F. Abou-Elfotouh //Thin Solid films.
1994, v. 237, p. 1–11.
2. H.W. Schock et. al. //J. Appl. Surf. Sc. 1996, v. 92, p.
606–616.
3. V.F. Gremenok, L.V. Bodnar//Proc. 17th EPSEC.
Germany, 2001.
4. S. Zweigart et. al. //J.Sol. Energy Mat. and Solar
Cells. 1996, v. 42, p. 219-229.
5. S.N. Grigorov et al. //Functional Materials. 1998,
v. 5(3), p. 335–342.
6. T. Wada et al. //Jpn. J. Appl. Phys. 2000, v. 39, N1,
p. 8–15.
7. A. Dimmler, H.W. Schock //Proc.10th ICTMC
Stuttgart, September, 1995.
8. J. Kessler, H.W. Schock //Proc.11th Europ. Photov.
Solar Energy Conf.(Montreux, 1992.
9. S.N. Grigorov et al. //Jpn. J.Appl.Phys. 2000,
v. 39, N1, p. 179–180.
10. T. Wada et al. //J. Crys.Res. Technol. 1996, v. 31,
p. 389–396.
11. T. Godeske et al. //Z. Metallkd. 2000, v. 91, N 8.
12. P.А. Pancheha, V.А. Novikov //Functional materi-
als. 2000, v. 7-4, N 2, p. 807–811.
ИССЛЕДОВАНИЕ ФАЗОВЫХ ПРЕВРАЩЕНИЙ В ДВУХСЛОЙНОЙ
ПЛЁНОЧНОЙ СИСТЕМЕ In2Se3-Cu
С.Н. Григоров, В.М. Косевич, С.М. Космачев, А.В. Таран
Проведены электронно-микроскопическое и рентгеноспектральное исследования плёнок Cu-In-Se, полученных
путём дозированного осаждения меди на слой селенида индия и отжига двухслойной композиции в атмосфере селена.
Были приготовлены образцы с различной концентрацией меди (Cu/In<1 и Cu/In>1). Установлено, что все пленки после
селенизации имеют модулированную структуру, которая формируется в результате диффузии меди в пленку селенида
индия. Наблюдались модулированные структуры, образованные как равновесными фазами, принадлежащими псевдоби-
нарному сечению Cu2Se-In2Se3 трехкомпонентной системы Cu-In-Se, так и метастабильными фазами.
ДОСЛІДЖЕННЯ ФАЗОВИХ ПЕРЕТВОРЕНЬ У ДВОШАРОВІЙ ПЛІВКОВІЙ СИСТЕМІ In2Se3-Cu
С.Н. Григоров, В.М. Косевич, С.М. Космачев, А.В. Таран
Проведені електронно-мікроскопічне та рентгеноспектральне дослідження плівок Cu-In-Se, отриманих шляхом
дозованого осадження міді на шар селеніду індію та відпалу двошарової композиції в атмосфері селену. Були
виготовлені зразки із різною концентрацією міді (Cu/In<1 і Cu/In>1). Установлено, що всі плівки після селенізації мають
модульовану структуру, що формується в результаті дифузії міді в плівку селеніду індію. Спостерігалися модульовані
структури, утворені як рівноважними фазами, що належать псевдобінарному перетину Cu2Se-In2Se3 трикомпонентної
системи Cu-In-Se, так і метастабільними фазами.
_________________________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2008. № 2.
Серия: Физика радиационных повреждений и радиационное материаловедение (92), с. 145-148.
148
1. INTRODUCTION
2. METHOD AND PREPARATION
3. RESULTS AND DISCUSSION
The samples of three types were prepared. According to EDS data, the samples of the first type were Cu-poor. Cu/In ratio was 0,64 as compared to a stoichiometric CIS. On the β-In2Se3-Cu2Se quasi-binary section of the Cu-In-Se equilibrium phase diagram, this chemical composition corresponds to the region of the β-CIS phase. The samples of the second type had the Cu/In ratio equal to 1,12, and the samples of the third type had a composition with Cu/In = 1,25. The samples of the second and third types were attributed to the two-phase (α-CuInSe2 + Cu2Se) region of the Cu-In-Se equilibrium phase diagram. All samples had an excess of Se as compared to stoichiometric CuInSe2.
CONCLUSIONS
REFERENCES
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